Prior alloy compositions comprising molybdenum are known, particularly for use in refractory applications such as fusion and fission reactors, rocket engine nozzles, furnace structural component and forging dies. Such applications require high hardness (as measured according to the Vickers hardness test) at a particular operating temperature. However, known molybdenum based alloy compositions have insufficient strength for some applications, particularly at high temperatures such as 1000 to 1100° C., and may have a high cost of production.
Examples of compositions of prior molybdenum based alloys are given in table 1, given in terms of weight percentages. TZM is described in further detail in U.S. Pat. No. 3,275,434. Further prior molybdenum based alloys are described in “The Engineering Properties of Molybdenum Alloys” by F F Schmidt and H R Ogden.
Each of these prior alloys may also comprise an amount of Rhenium. The inclusion of rhenium in a molybdenum alloy is thought to improve ductility, recrystallization temperature and strength. However, rhenium is an expensive elemental addition, due to its relative scarcity in the earth's crust. Rhenium containing alloys may therefore have an unacceptably high cost.
The present invention describes an alloy composition and an article comprising the alloy composition which seeks to overcome some or all of the above problems. All percentage amounts are given in terms of weight percentages unless otherwise specified.